1. Field of the Invention
The present invention relates to a device for checking to be sure that a filler cap, particularly of such a kind that is screwed into a threaded filler tube of an automobile fuel tank, is properly installed.
2. Description of the Prior Art
It is usual for a driver to leave handling of a fuel tank filler cap entirely to a gas station worker. The driver does not check the filler cap for proper installation by himself. However, it does not always follow that a gas station worker installs a filler cap properly. Should the filler cap be installed loosely, not only gasified fuel in the fuel tank would leak to contaminate the air but also such leakage of fuel would be likely to occur upon collision that causes a disastrous accident.